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A new Differential Plunger device for measuring pico‐second lifetimes of Unbound Nuclear States (DPUNS) is being built at The University of Manchester. DPUNS has been designed to work with alpha‐, beta‐ and isomer‐tagging methods using the existing JUROGAM II—RITU—GREAT infrastructure at the University of Jyvaskyla, Finland. The importance of proton emission from nuclei is that it provides valuable nuclear‐structure information as direct input to nuclear models beyond the drip line. New experimental data beyond the drip line can provide new extensions to these models especially with the possible coupling of weakly bound and unbound states to the continuum. The results of the first experiments to measure lifetimes of unbound nuclear states with this method was discussed along with possible future experiments which can be addressed with DPUNS using proton‐, isomer‐ and alpha‐tagging.

The Recoil‐Distance Doppler‐shift method has been combined with Recoil‐Decay Tagging for the first time to measure a lifetime in the proton‐unbound nucleus 109I. The lifetime value was determined using the Differential Decay‐Curve method in singles mode. The result has been compared to theoretical shell‐model calculations in order to better understand the nature of unbound valence nucleons at the proton drip line.

This contribution focused on research to measure the lifetimes of unbound nuclear states using a differential‐plunger technique combined with recoil‐proton decay tagging. The results of the first lifetime measurements of unbound states in the spherical proton emitter, 109I, were discussed along with the limits to the technique. In order to proceed further, a new differential‐plunger device, DPUNS, has been designed and is currently being built at the University of Manchester. DPUNS has been optimised to work with the GREAT/RITU/TDR setup at the University of Jyvaskyla and the status of the new device is discussed.

This paper summarises the programme of Recoil-isomer tagging that has been performed over the last ten years at the University of Jyvaskyla, Finland. The nuclei studied lie in the mass 130-140 region of the Segre chart very close to the proton drip line. The evolution of the isomer character is seen to change from K-isomers, at N=74, to shape-isomers in the gamma soft N=77 nuclei to seniority-isomers around N=82. The influence of the proton drip line on the N=74 isomers and possible critical-point symmetries in the N=77 nuclei are discussed and the latest results presented. Developments of the isomer-tagging technique, using large beam currents with a dual Mufti-Wire Proportional Counter setup, and an Isomer-tagged Differential-Plunger setup are discussed along with a future programme of work at Jyvaskyla.

This report details the status of an experimental research programme which has studied isomeric states in the mass 130–160 region of the nuclear chart. Several new isomers have been established and characterised near the proton drip line using a recoil isomer tagging technique at the University of Jyvaskyla, Finland. The latest experiments have been performed with a modified setup where the standard GREAT focal‐plane double‐sided silicon‐strip detector was changed to a dual multi‐wire proportional‐counter arrangement. This new setup has improved capability for short‐lived isomer studies where large focal‐plane rates can be tolerated. The results of key recent experiments for nuclei situated above (153Yb, 152Tm) and below (144Ho, 142Tb) the N = 82 shell gap were presented. These studies have charted the evolution of isomeric states across the neutron shell from K‐Isomers at N = 74, to shape isomers at N = 77 and shell‐model isomers at N = 82, 83. The excitation energies for some of the lowest‐lying excited states in these isomeric nuclei show behaviour which is characteristic of an X(5) symmetry falling midway between the limits expected for pure vibrational and rotational behaviour. The future prospects for studies of these nuclei were discussed using an isomer‐tagged differential‐plunger setup. This technique will be capable of establishing the deformation of the states above the isomers and will aid in determining whether their behaviour is indeed well described by the X(5) symmetry limit.

This report details the status of an experimental research programme which has studied isomeric states in the mass 130–160 region of the nuclear chart. Several new isomers have been established and characterised near the proton drip line using a recoil isomer tagging technique at the University of Jyvaskyla, Finland. The latest experiments have been performed with a modified setup where the standard GREAT focal‐plane double‐sided silicon‐strip detector was changed to a dual multi‐wire proportional‐counter arrangement. This new setup has improved capability for short‐lived isomer studies where high focal‐plane rates can be tolerated. The results of key recent experiments for nuclei situated above (153Yb,152Tm) and below (136Pm,142Tb) the N = 82 shell gap were presented along with an interpretation for the isomers. Finally, the future prospects of the technique, using an isomer‐tagged differential‐plunger setup, were discussed. This technique will be capable of establishing the deformation of the states abo...

This paper reviews the past, present and future status of recoil‐isomer tagging at the University of Jyvaskyla. The main focus of this research has been to access isomeric states at and beyond the mass ≈140 proton drip line. Recoil‐isomer tagging was first used at the University of Jyvaskyla in 1998 to establish the prompt rotational band built upon a Kπ = 8− isomeric state in 138Gd. Since that time a series of experiments have been performed which have studied isomeric states in the N = 77 isotones 63140Eu77, 65142Tb77 and 67144Ho77, and in the N = 74 K‐isomer chain, 64138Gd74 and 66140Dy74. These experiments have revealed valuable first information about deformations, single‐particle excitation energies and hindrance factors in nuclei at and beyond the proton drip line where little or no information previously existed.The results of the most‐recent experiments were discussed. These experiments established new isomeric states in 66143Dy77, 61136Pm75, and 64137Gd73 and a further two isomers which are curr...

Two Gammasphere experiments have been performed in order to establish the possible triaxial nature of strongly deformed (SD) bands in 174Hf. A lifetime measurement confirmed the large deformation of the four previously observed bands in this nucleus. In addition, a thin‐target, high‐statistics experiment was carried out to search for linking transitions between the SD bands. No such transitions, which represent an experimental signature for wobbling modes, were observed. Four new SD bands were found in 174Hf together with a single SD band in 173Hf. These results indicate that the strongly deformed sequences of N ≈ 102 Hf isotopes behave differently than the TSD bands found in Lu nuclei near N = 92. The interpretation of these bands in terms of possible stable triaxial deformation is confronted with the experimental findings and UC predictions.

Deep-inelastic collisions of 136Xe ions with tantalum and tungsten targets have been used to study high-spin isomers in neutron-rich A≈180 nuclei at the GSI on-line mass separator. Gamma-rays associated with the decay of the well known Kπ=37/2−, 51-minute isomer in 177Hf were observed, but with different half-life characteristics and an unexpectedly high yield. These features are interpreted as evidence for a hitherto unrecognized isomer in 177Lu. A two-component half-life analysis of the 177Hf γ-ray intensities gives a first component of 6−2+3 min, when the second component is fixed at 51 min. Comparison with multi-quasiparticle calculations suggests the possibility of a Kπ=39/2− isomer in 177Lu, which β-decays to the 177Hf isomer. This would be the highest-spin β-decaying state yet identified.

Levels schemes for a number of low lying normally deformed bands in {sup 161,162}Er have been extended to significantly higher spins than hitherto using the EUROBALL Ge detector array sited at the Legnaro National Laboratory. In the case of one band in {sup 161}Er states have tentatively been observed to a spin in excess of 60({Dirac_h}/2{pi}). Evidence is found for a band crossing at high spin in the yrast even parity, positive signature (+, +1/2) band in {sup 161}Er. This can be explained in terms of a system in which the static pairing is quenched either involving a rearrangement of two neutrons into steeply aligning i{sub 13/2} orbitals or possibly an interchange of state of one proton and one neutron. A similar type of band crossing is tentatively identified in the lowest (-,-1/2) band of {sup 161}Er. Since a crossing involving the interchange of neutrons is blocked, this must involve protons. This, if confirmed, provides the first direct evidence for the quenching of static proton pairing at high spin in this mass region. Recent calculations [1] predict that such a crossing involving purely protons will occur in this band at I{approx}60({Dirac_h}/2{pi})

This contribution focussed on studying nuclear pairing via its effects on the nuclear moment of inertia using K-isomeric states as a probe. The reason for studying the effects on K-isomeric states is that their underlying single-particle configuration can be uniquely defined through a measurement of the in-band to out-of-band branching ratios. The angular momentum limits to populating K-isomers were also addressed.

High-spin states in 163,164Lu have been populated in the 139La(29Si,xn) reaction and their decay has been studied using the EUROBALL γ-ray spectrometer array. In 164Lu eight new superdeformed (SD) bands have been found. In 163Lu the previously known SD band is extended to lower and higher spins and its deacy to the normal-deformed states has been established. In addition, a new SD band is identified. Calculations with the Ultimate Cranker code predict large triaxiality (γ≈±20°) for all these bands.

High-spin states up to the f7/2-shell band termination at J*=15+ have been observed for the first time in the odd-odd N=Z=23 nucleus 46V. The new level scheme has two separate structures corresponding to spherical and prolate shapes. A rotational band has very similar energies to the yrast sequence in 46Ti and is therefore assumed to be a T=1 configuration.

A brief reminder is given of the evidence for the existence of octupole correlations in the superdeformed shape of 193Hg. It is pointed out that comparison of the data on the superdeformed bands in 19Hg with Cranked Shell Model calculations gives firm assignments to the signatures and parities of these bands. The spin assignments obtained are in agreement with the spin assignments given by projecting the SD bands back to zero rotational frequency and assuming the intrinsic alignment i0 is zero. These spin asssignments leave ‘‘identical’’ bands in 191Hg, 193Hg and 194Hg with a surplus 1ℏ of spin relative to the superdeformed core nucleus 192Hg. This extra 1ℏ of alignment is not understood.